Oxygen concentrator



FIG. 1 is a perspective view of an oxygen concentrator, showing the new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left-side view thereof;

FIG. 5 is a right-side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines are included for the purpose of illustrating portions of the oxygen concentrator that form no part of the claimed design. 

CLAIM The ornamental design for an oxygen concentrator, as shown and described. 